In Greek myth, Cerberus, also known as Kerberos, is a monster and pet under Hades that guards the gates of the Greek underworld, the realm of Hades. It is generally depicted as a vicious, gargantuan dog with three heads, although accounts may vary. Cerberus is in fact the Latin transliteration of the Greek name Kerberos.
Cerberus was one of the monsters born from the union of Echidna and Typhon, both as monstrous and hideous as their offspring. Echidna was half-woman, half-serpent, while Typhon was the most fierce of all creatures. Among his brothers, the most famous are Hydra, Chimera, and Orthrus.
Cerberus is encountered like any other demon near the end of the Tower of Daedalus within a corridor on the way to Valhalla. He is also featured on the game's startup screen and graphics, and appears in stills from the Digital Devil Story: Megami Tensei OVA printed within the game manual. He is unusually strong for a demon available so early in the game, with extremely high VIT and access to Recarm long before these things are available in any other way.
Cerberus may be encountered and welcomed into the protagonist's party via an optional side quest which entails gaining access to the Intelligence Building, by which the protagonist's party is able to re-enter the Devil Busters video game. He is found on the 1st Floor of the Tower of Daedalus and must be recruited before fighting Nidhoggr. When recruited, he states he has been waiting for the protagonist for more than a century.
In Megami Tensei, if Cerberus is in the protagonist's stock, a man in the northern-central area of Valhalla will ask the party if they would like to enter Hell. The area is a teleport maze where the COMP cannot be used, however the Mappara spell still works. At the end of the dungeon, when the protagonist leaves, Cerberus stays behind to "prevent the dead from escaping."
"Origin: Greece. The guard dog of the gates of Tartarus. It has three heads and a snake's tail, and is the son of Echidna and Typhon, god of storms. It viciously attacks both the living who near the gates, and the dead who try to escape."
—Shin Megami Tensei A-Mode DDS dictionary
After having his mother killed and eaten by a demon, the protagonist can choose to add his dog, Pascal, into his party. In normal circumstances, Pascal serves as a low level ally. However, when fused with a demon in the Cathedral of Shadows, he transforms into the high level demon Cerberus. Because Pascal's former loyalty towards his master passes on to him through fusion, Cerberus can be used even when his level far surpasses that of the protagonist; something that is generally impossible. He aids him in only one boss battle however, disappearing through a Terminal after that boss fight.
Much later in the game, Cerberus stands on the bridge that leads to Tokyo Destinyland in a berserk state that can only be reversed if the protagonist possess the valuable "Golden Apple." Because of the power of this item to stabilize violent demons, Cerberus comes back to his senses and recognizes the protagonist, thus choosing to share his fate by joining his party.
Cerberus is summoned by Gagyson in order to kill Kojiro, who poses a threat to Gagyson's plans. Although he succeeds in killing Kojiro's dog Patra, he is stopped from finishing Kojiro thanks to a monk. The monk then defeats Cerberus and gives him an ultimatum: protect Kojiro or die. Choosing the former, he betrays Gagyson and takes the form of Patra while guarding him. After Ose is summoned, he becomes the steed of Kojiro after the human incarnates into his true form, Masakado.
Cerberus first joins Aleph on the first quest Madam gives him: find and bring back Hanada. After this quest, he leaves the party. Later, when Valhalla is swallowed by Abaddon, he will be found at the former entrance to the city from the underground passageway. He joins Aleph's party shortly after meeting him for the second time.
It is revealed in extra visionary scenes in the GBA and iOS versions that he is the same Cerberus from Shin Megami Tensei, and maintains Pascal's memories and consciousness.
At the beginning of the game, a broken floppy disk can be found on the ground of the second floor of Karukozaka High School. The disk can then be taken to Katsuhiko Sato, the president of the school's computer club who will attempt to fix it, releasing the Cerberus that was stored inside once the protagonist has completed the World of Sloth. Katsuhiko then runs away from the demon and asks the protagonist to help. Cerberus, angry at being trapped inside the disk, demands that the protagonist let him pass. If they refuse, Cerberus will start a fight right there. If they comply, Cerberus will go but can be found in the storage room on the first floor. After being defeated, he'll recognize the strength of the protagonist and join the party despite the massive difference of levels.
Cerberus is an optional boss faced after completing Chernobog's challenge. Madam will call the protagonist and Ain to bring back her pet who has ran away. After being found, Cerberus appears to be brainwashed and attacks the party. Defeating it makes him summonable through fusion.
"The feared guard dog of hades in Greek mythology. His parents were the giants Typhon and Echidna. He is the brother of Orthrus."
—Shin Megami Tensei III: Nocturne compendium
Cerberus first appears at the Burial Chamber in the Amala Labyrinth's First Kalpa, where he will challenge the Demi-fiend to prove his worth as a demon by quickly vanquishing once more those that he has killed in the Vortex World using the Black Visor. After meeting all the requirements and starting a new cycle, meeting with Cerberus again in the same location will have him take the Demi-fiend to his master's resting place instead at the Tomb of Yomi in the hidden 666th floor, where he will receive an extra Press Turn.
Cerberus can also be encountered and recruited inside the Diet Building.
"The Hound of Hell in Greek mythology. Its name means "Demon of the Pit". It is known as the loyal servant of Hades, the king of the Underworld. Cerberus was born from the union of the half-serpent Echidna and the storm giant Typhon. The two-headed beast Orthrus is his brother. Cerberus appears as a three-headed dog with with snakes all over his body and a dragon's tail. The three heads are said to represent the past, the present and the times yet to come. Cerberus guards the gates of the Underworld, the realm of the dead, welcoming souls of the dead from the outside world, but ferociously attacking all those who attempt to leave. It was traditional in ancient Greece to place a copper coin and a honeycake in coffins. This was so that the departed souls could pay Charon, the boatman of the river Styx, to ferry them across the river, and feed Cerberus, who favored sweets."
—Shin Megami Tensei IMAGINE compendium
Cerberus is among the first demons to contract with the player as an injured demon that requests Snakeman to allow it to assist the player. This Cerberus is the former demon partner of DB Kuroe, the player's mentor from the tutorial and during the story he'll need to be returned to Snakeman. Once reaching level 30, a player regains the Cerberus as a stronger variation. Cerberus can be encountered within the gold level instance of Suginami Tunnels and appears regularly as a boss within the main storyline and as the final boss of the Suginami Tunnels Unknown plate boss rush. In the later acts, Cerberus is an intermediary for the leader of Protopia, Madam Justice, in giving story missions until a player has fully committed to the neutral route of the final acts. Within the neutral route, he is the boss players must defeat to gain access to the Ring of Human Being necessary to access the fight with Seth in Act 20.
Cerberus is the tutorial mountable demon and among the regular mounts within the game. Variations using the three-headed model from Digital Devil Saga can be acquired through events, special fusions or a plug-in variant acquired through Shinjuku's Gomory called Asura Cerberus that learns the special skills Phlegethon and Pyriphlegethon.
Cerberus is fought in the Challenge QuestBanquet of Flames. The quest involves an enraged Cerberus on a rampage around Tokyo, provoking local hunters to set a quest out for his defeat. After multiple encounters, Cerberus eventually calms down and returns to his realm.
"The guardian hound of Hades in Greek lore. It traditionally has three heads and a snake's tail. It was born from Typhon, the giant of wind, and Echidna, the mother of monsters."
—Shin Megami Tensei IV Apocalypse compendium
Cerberus can be found in Camp Ichigaya or evolve from Orthrus once it reaches level 64, provided that Nanashi can control the result. It can teach Nanashi the Agidyne, Madness Nails and War Cry skills through its Demon Whisper. Cerberus benefits from learning Fire and Physical skills.
"The guardian hound of Hades in Greek mythology. It traditionally has three heads and a snake's tail. It was born from Typhon, the giant of wind, and Echidna, the mother of monsters."
—Devil Summoner: Soul Hackers 3DS compendium
Cerberus possesses the Loyalty Slash technique, and until the 3DS remake this was his signature move.
In the 3DS remake, a variant Cerberus can be purchased from Nemechi (dango form), and costs 300 D-Souls. His artwork is based on his traditional design from the first Shin Megami Tensei. This version loses his vulnerability to Ice magic and is better suited at casting spells, but does not have Loyalty Slash.
Cerberus appears as Koromaru's initial Persona. It is a Fire and Darkness elemental Persona and differs from the usual appearance as a black three-headed hound resembling a Doberman. The original Cerberus can also be accessed and used by the protagonist by using a cheat device.
After the two heroes complete the request, The Power of the Wild Card, Margaret explains to everyone how their Personas can now evolve and attain new power. Koromaru and Shinjiro stick around after everyone else is dismissed, and ask if it is possible for them to keep their Personas, rather than attaining new ones. Koromaru explains, through Aigis, that he awakened his persona when Shadows attacked the shrine he used to protect with his owner, and he now uses it to protect his deceased owner's house; he says that he does not want his Persona to change so that he can never forget his failure to protect his owner. Margaret tells them that it should be possible for their Personas to remain the same if they focus on keeping things the same when they start to attain new power.
Cerberus is summoned alongside Cu Chulainn by Goro Akechi to face the Phantom Thieves in Shido's Palace. Akechi induces madness in the two Shadows, greatly increasing their physical strength. Upon their defeat Akechi faces the party himself.
Cerberus is the Atma Avatar of Lupa, the leader of the Wolves. He serves as the boss fight in the Samsara Waterways. In this title, Cerberus appears as a three-headed, eyeless beast.
The battle will begin as soon as the party reaches the light at the top of the ramp, across from the Large Karma Terminal that is designated Samsara Tunnels 3. Unlike most bosses so far, Cerberus does not have an actual weakness and resists everything aside from Ice and Physical attacks. Cerberus also has the High Counter and Counterstrike skills, which makes Physical attacks without retaliation difficult.
Cerberus has three heads, each of which fulfill a different role. Cerberus (R) uses buff and debuff spells along with Ice Repel. Cerberus (L) acts as a healer, but will focus on healing the center head. Finally, Cerberus (C) is the main attacking head. Each head grants Cerberus one press turn, so destroying a head will reduce the number of turns Cerberus can take.
"The guardian hound of Hades in Greek lore. Traditionally has three heads and a snake's tail. He was born from Typhon, the giant of wind, and Echidna, the mother of monsters. he is also Orthrus' older brother."
Cerberus serves as Yamato's main demon. Its status serves as a nod to a scene early in the game where Yamato uses it to dispatch some demons before showing the JP's underground trains to the party. He summoned it at the young age of 5, and it has accompanied him ever since. To date, Yamato has used Cerberus in fending off Phecda and Megrez.
"A large three-headed beast from Greek mythology, guard dog of the gateway to the underworld and often depicted with a snake for a tail. Born to the giant of wind Typhon and the snake Echidna, its brother is Orthrus."